How does a one time high traffic from a different source affect my google ranking?

Hey guys,

we just started a big newsletter campaign and got about 15-20 times the normal traffic from clicks on the newsletter links, but the conversion was pretty bad.
Since the traffic did not come from google directly, I am curious if and how that could affect our ranking on google.

Start Social Sharing, it can help you to boost Traffic, also write relevant content and index it, start guest blogging.

You never want to send mass emails from your website domain, in fact, many hosting servers do not allow the sending of mass mail.
When sending mass mailings or for maintaining and obtaining large mailing lists you should always use a mail system like MailChimp, Constant Contact etc.
If people click on the email links and do not abuse your email, then certainly there will not be a problem.
I strongly suggest you use a mail service and place a mailing sign-up form on your site and encourage users to sign-up for your newsletters.
This is the best way to ensure high open rates.